title: Genetic variability of mutans streptococci revealed by wide whole-genome sequencing.
abstract: BACKGROUND
  Mutans streptococci are a group of bacteria significantly contributing to tooth decay. Their genetic variability is however still not well understood.
  
  
  RESULTS
  Genomes of 6 clinical S. mutans isolates of different origins, one isolate of S. sobrinus (DSM 20742) and one isolate of S. ratti (DSM 20564) were sequenced and comparatively analyzed. Genome alignment revealed a mosaic-like structure of genome arrangement. Genes related to pathogenicity are found to have high variations among the strains, whereas genes for oxidative stress resistance are well conserved, indicating the importance of this trait in the dental biofilm community. Analysis of genome-scale metabolic networks revealed significant differences in 42 pathways. A striking dissimilarity is the unique presence of two lactate oxidases in S. sobrinus DSM 20742, probably indicating an unusual capability of this strain in producing H2O2 and expanding its ecological niche. In addition, lactate oxidases may form with other enzymes a novel energetic pathway in S. sobrinus DSM 20742 that can remedy its deficiency in citrate utilization pathway.Using 67 S. mutans genomes currently available including the strains sequenced in this study, we estimates the theoretical core genome size of S. mutans, and performed modeling of S. mutans pan-genome by applying different fitting models. An "open" pan-genome was inferred.
  
  
  CONCLUSIONS
  The comparative genome analyses revealed diversities in the mutans streptococci group, especially with respect to the virulence related genes and metabolic pathways. The results are helpful for better understanding the evolution and adaptive mechanisms of these oral pathogen microorganisms and for combating them.
authors.affiliation: Institute of Bioprocess and Biosystems, Technical University Hamburg Harburg, Hamburg Harburg, Germany.
authors.forename: Lifu
authors.initials: L
authors.lastname: Song
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Georg
authors.initials: G
authors.lastname: Conrads
authors.forename: Anke
authors.initials: A
authors.lastname: Rheinberg
authors.forename: Helena
authors.initials: H
authors.lastname: Sztajer
authors.forename: Michael
authors.initials: M
authors.lastname: Reck
authors.forename: Irene
authors.initials: I
authors.lastname: Wagner-Döbler
authors.forename: An-Ping
authors.initials: AP
authors.lastname: Zeng
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002869:Chromosome Aberrations; D024881:Drug Resistance, Bacterial / Q000235:genetics; D019143:Evolution, Molecular; D014644:Genetic Variation; D016680:Genome, Bacterial / Q000235:genetics; D023281:Genomics; D053858:Metabolic Networks and Pathways / Q000235:genetics; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D018384:Oxidative Stress / Q000235:genetics; D017421:Sequence Analysis; D013295:Streptococcus mutans / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C423628:competence factor, Streptococcus